@CharityAdams - Unfortunately you can only @mention team members and not guests.

More on this in the @Mentioning People on the Board Help Center article.

I can understand why the @mention feature only works for team members, e.g., Miro wouldn’t know exactly who you were tying to mention, however, if they were on the board, Miro could potentially open up the @mention search to why users on the board.

I’d recommend adding this as an Idea in the Wish List category by following the guidelines here: Wish List: Everything You Need to Know.

If you do create a Wish List Idea post, I would also recommend that you post a link to it back here, so that future readers of this post can quickly get to and vote for your Idea.

Lastly, don't forget to vote for your own Idea.

Guests can now login with their email and select a user name but I still cant mention them, am I doing something wrong or is this feature still unavailable?

@David Chávez 

Guests can now login with their email and select a user name

Miro does not have a “user name”, so are you referring to the following prompt when accessing a board?

If so, then only someone accessing a board while not signed into a Miro account would see this.

My next question would be: Are you using Visitor or Guest access?

Visitor access is when you set a board’s Share settings to Anyone with the link → Can edit and send the a link to the board. With this access, Visitors cannot be mentioned:

Source: https://help.miro.com/hc/en-us/articles/360012524559-Collaboration-with-visitors

Guest access is when you add a user to the board at the top of the Share settings windows - note: This feature is currently in beta and you may not have access to it.

More on Collaboration with guests (BETA) and how to use it:

https://help.miro.com/hc/en-us/articles/360021415119-Collaboration-with-guests-BETA-